1. Field of the Invention
The present invention relates to novel ferrocene derivatives, surfactants containing them and a process for producing organic thin films, and more particularly to novel ferrocene derivatives having a structure with a main carbon chain bonded to a ferrocene skeleton in which chain an arylene group such as phenylene is contained or a substituted or unsubstituted phenyl group is bonded as a branch chain; surfactants containing the abovedescribed ferrocene derivatives, and capable of making hydrophobic organic substances including phthalocyanine soluble, and a process for producing a thin film of a hydrophobic organic substance using these surfactants.
2. Description of the Related Arts
In general, coloring materials such as phthalocyanine or its derivatives are insoluble in water, and although they are soluble in organic solvents such as dimethylformamide (DMF), tetrahydrofuran (THF) and the like, their solubility is as small as several milligrams.
Surfactants to dissolve phthalocyanine and the like in water have heretofore been investigated, but a satisfactory one has not been developed. It is reported that phthalocyanine derivatives substituted with a functional group can be dissolved in water to some extent with the use of sulfone-based surfactants. The solubility therein, however, is not always sufficiently high, and, what is worse, unsubstituted phthalocyanines are not dissolved at all.
In connection with water-insoluble polymers, surfactants to make them soluble in water have been investigated similarly to the above, but a satisfactory result has not been obtained.
The present inventors' group have previously developed ferrocene derivatives containing a polyoxyethylene chain as surfactants to make soluble coloring materials such as phthalocyanine, its derivatives, water-insoluble polymers and the like, and at the same time, they have developed a process for forming an organic thin film by applying so-called Micellar Disruption Method by use of said ferrocene derivatives (PCT/JP88/00855, published on Mar. 9, 1989 under WO 89/01939).
The present inventors have made extensive investigations to develop a process for improving the abovementioned surfactants, improving the electrolytic ability in the Micellar Disruption Method while maintaining a high capability of making hydrophobic organic substances soluble, making the oxidation-reduction reaction of ferrocene derivatives proceed smoothly, and further improving the productivity of organic thin films.
As the result, it has been found that the object can be attained by ferrocene derivatives having a novel structure in which an arylene group such as a phenylene group is contained in the substituent of the long chain bonded to the ferrocene skeleton, or a substituted or unsubstituted phenyl group is bonded as branch chain to the long chain. The present invention has been completed based on the findings described above.